1. Field of the Invention
This invention relates to internal combustion engines and, more particularly, to an air filter for use with internal combustion engines.
2. Prior Art
Various different types of choke valves and spitback shields are known in the internal combustion engine art. In U.S. Pat. No. 4,495,911 to Andreasson, a choke device located in the air filter of an internal combustion engine is disclosed. U.S. Pat. No. 1,105,090 discloses an air valve for carburetors. U.S. Pat. No. 4,539,162 discloses a choke assembly for a golf cart. U.S. Pat. No. 3,746,320 discloses a fuel feed and charge forming method and apparatus with an inlet region having a choke band of a venturi-like shape.
However, various different problems still exist with presently available devices. First, it is desirous to substantially reduce or eliminate contamination of the filter elements in the air filter by fuel which is spitback from the carburetor. Spitback can generally be described as the ejection of fuel particles out of the carburetor air intake into the air filter. Spitback can contaminate the air filter element causing dust particles and the like to become caked on the filter elements and thereby clog the filter elements and prevent a proper air-fuel mixture from being obtained. Second, in some situations, it is desirous to provide components as small or compact as possible such as for reduction in the size and weight of the engine. This is particularly important for hand held devices such as chain saws or grass trimmers. Third, it is desirous to provide an air filter for an engine that is a cartridge type air filter for easy removal or replacement.
A problem exists in the prior art in that, although spitback shields are known in the art and may be able to accelerate inlet air velocity proximate these shields, no spitback shield has provided both a fuel accumulation surface as well as means for containing accumulated fuel spitback with the shield for re-injection into the carburetor. This problem is clearly evident during conditions of severe or prolonged fuel spitback when the rate of fuel spitback is greater than the rate of re-injection of the fuel into the carburetor. This can result in large amounts of fuel spitback accumulating on the shield to such a degree that the fuel can drip or vibrate off of the shield and onto the filter elements.
A further problem exists in the air filters of the prior art in that no air filter is provided that can collect spitback fuel, contain the collected spitback fuel and allow for the atomization and re-injection of the contained fuel spitback fuel into the carburetor of an engine.
It is therefore an objective of the present invention to provide an improved fuel spitback shield for use in an air filter that can contain relatively large amounts of accumulated spitback fuel.
It is a further objective of the present invention to provide an improved fuel spitback shield which is space efficient and has means for both collecting and containing spitback fuel.
It is a further objective of the present invention to provide an improved cartridge air filter having a spitback shield and fuel spitback atomizer.